encrypt username and password

My workplace IT claims that my email client has been 
transferring my user name and password information in 
unencrypted clear text.  I am supposed to fix this.
Are they likely to be right?  How can I tell?
If they are right, how can I fix this?

I use IMAP.
In my network preferences, I have:
        SSL/TLS for SMTP server: use SSL only

Thank you,
Alan Isaac






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